The invention relates to a heat exchanger, in particular a coolant condenser which has a plurality of flat pipes extending in parallel, and corrugated ribs are arranged between the flat pipes, wherein the ends of the flat pipes are connected to corresponding openings in the base of junction boxes of solder-plated material and being soldered to the junction boxes. A heat exchanger of this kind is known from EP-A-O,255,513. With this condenser the ends of extruded flat pipes are passed into elongated slots of a tubular junction box and soldered to the junction box. With production of this kind, the ends of the flat pipes must correspond exactly to the size of the slots so that tightness of the soldering point is achieved. The corrugated ribs are provided with a layer of solder in order to be soldered to the flat pipes which do not have any solder. With the known arrangement it is necessary for different junction boxes to be produced for different pipe cross sections, general use of one uniform type of junction boxes for different pipe cross sections is therefore not possible.
U.S. Pat. No. 3,689,972 describes a process, by means of which, with a flat pipe heat exchanger, after soldering the pipes into the junction boxes, the junction boxes are deformed to a desired cross sectional shape. Since the soldering of flat pipes into corresponding slots of junction boxes, in particular in the region of the parallel flat sides, is problematic, EP-A-O,198,581 proposed providing the base of the junction boxes with curves, by means of which the soldering of the flat pipes to the junction boxes should be improved.
Moreover, it is known from U.S. Pat. No. 3,857,151 with a flat pipe heat exchanger to shape the pipe ends to a round cross section in order to fasten the pipe in a pipe plate without soldering. However, for this kind of pipe/base connection it is necessary for a correspondingly long connection surface to be present between pipe and base in order to ensure the required strength and tightness. However, it has been established that non-soldered connections are not coolant-tight such that non-soldered heat exchangers can only be applied to a restricted extent and are unsuitable for coolant circuits.
A heat exchanger suitable for coolant circuits is described in DE-A-3,622,953. This heat exchanger consists of flat pipes, the pipe ends of which are extended in relation to the central sections, the parallel sides of the ends of in each case adjacent pipes lying next to one another. This heat exchanger does not have junction boxes because the pipe ends lying next to one another of the parallel flat pipes are connected to one another and, in this manner, take over the function of the junction boxes.